Lipid phase separations and protein distribution in membranes

1974 ◽  
Vol 2 (5-6) ◽  
pp. 609-616 ◽  
Author(s):  
W. Kleemann ◽  
C. W. M. Grant ◽  
H. M. McConnell
Keyword(s):  
Lipid Phase ◽  
Protein Distribution ◽  
Phase Separations

Thermotropic lipid phase separations in human platelet and rat liver plasma membranes

1983 ◽  
Vol 76 (2) ◽  
pp. 139-149 ◽  
Author(s):  
Larry M. Gordon ◽  
Patrick W. Mobley ◽  
Judy A. Esgate ◽  
Gary Hofmann ◽  
Anthony D. Whetton ◽  
...  
Keyword(s):  
Rat Liver ◽  
Plasma Membranes ◽  
Human Platelet ◽  
Lipid Phase ◽  
Phase Separations ◽  
Liver Plasma Membranes ◽  
Rat Liver Plasma Membranes

scholarly journals Guanosine 5′-triphosphate and guanosine 5′-[βγ-imido]triphosphate effect a collision coupling mechanism between the glucagon receptor and catalytic unit of adenylate cyclase

1980 ◽  
Vol 186 (3) ◽  
pp. 649-658 ◽  
Author(s):  
Miles D. Houslay ◽  
Irene Dipple ◽  
Keith R. F. Elliott
Keyword(s):  
Adenylate Cyclase ◽  
Plasma Membranes ◽  
Specific Binding ◽  
Regulatory Protein ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Lipid Phase ◽  
Trypsin Treatment ◽  
Phase Separations ◽  
Catalytic Unit

1. GTP, but not p[NH]ppG (guanosine 5′-[βγ-imido]triphosphate), abolishes the sensitivity of glucagon-stimulated adenylate cyclase to the lipid-phase separations occurring in the outer half of the bilayer in liver plasma membranes from rat. 2. When either GTP or p[NH]ppG alone stimulate adenylate cyclase, the enzyme senses only those lipid-phase separations occurring in the inner half of the bilayer. 3. Trypsin treatment of intact hepatocytes has no effect on the basal, fluoride-, GTP- or p[NH]ppG-stimulated adenylate cyclase activity. However, 125I-labelled-glucagon specific binding decays with a half-life matching that of the decay of glucagon-stimulated adenylate cyclase activity. 4. When GTP or p[NH]ppG are added to assays of glucagon-stimulated activity, the half-life of the trypsin-mediated decay of activity is substantially increased and the decay plots are no longer first-order. 5. Trypsin treatment of purified rat liver plasma membranes abolishes basal and all ligand-stimulated adenylate cyclase activity, and 125I-labelled-glucagon specific binding. 6. Benzyl alcohol activates the GTP- and p[NH]ppG-stimulated activities in an identical fashion, whereas these activities are affected differently when glucagon is present in the assays. 7. We suggest that guanine nucleotides alter the mode of coupling between the receptor and catalytic unit. In the presence of glucagon and GTP, a complex of receptor, catalytic unit and nucleotide regulatory protein occurs as a transient intermediate, releasing a free unstable active catalytic unit. In the presence of p[NH]ppG and glucagon, the transient complex yields a relatively stable complex of the catalytic unit associated with a p[NH]ppG-bound nucleotide-regulatory protein.

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